The present invention relates to the art of presses and, more particularly, to opposed slide double acting presses having a bolster assembly between the slides.
The present invention finds particular utility in connection with opposed slide double acting presses having a bolster assembly between the slides and which bolster assembly and slides support corresponding tooling which is cooperable to cut a circular blank from flat sheet metal and to draw the circular blank to a cup-shaped contour. Accordingly, the invention will be disclosed and described in detail with regard to a press and tooling construction for this purpose. At the same time, it will be appreciated that the bolster arrangement in accordance with the present invention can be employed with opposed slide double acting presses in which tooling on the bolster assembly and slides is cooperable to perform work other than the cutting and drawing of sheet metal blanks.
Double acting presses having opposed vertically reciprocable upper and lower slides and an intermediate bolster assembly are advantageous for a number of reasons in connection with metalworking operations which require the characteristics of a double acting press, namely a first slide having tooling cooperable with tooling on the bolster to cut and hold a blank and a second slide having tooling cooperable with tooling on the bolster to form or shape the blank. Among the advantages of an opposed slide double acting press having an intermediate bolster assembly is the fact that both slides have a maximum tool supporting area available for use, whereby a larger number of articles can be produced during each cycle of press operation. A further advantage resides in the fact that the two slides in an opposed slide construction are independently supported for reciprocation relative to the press frame, thus avoiding undesirable guidance and vibration characteristics encountered in connection with the inner slide of a conventional double acting press wherein the outer slide is guided by the frame and the inner slide is guided by the outer slide. Still further, in an opposed slide double acting press in which the slides move toward and away from the intermediate bolster assembly, acceleration and deceleration forces of the slides tend to cancel each other whereas in a double acting press in which both slides move in the same direction, the acceleration and deceleration forces of the slides are partially additive.
It is of course well known that press tooling such as blank cutting dies, forming dies, drawing dies and drawing punches require frequent inspection to determine the condition thereof and, when necessary, removal of the tooling is required for repair and/or replacement purposes. In an opposed slide double action press, such inspection of the tooling while the latter is within the confines of the press is extremely difficult, especially where such inspection requires determination of the condition of interior portions of die cavities or the like. Furthermore, such inspection of tooling within the confines of the press is time consuming and subjects personnel to potential hazardous working conditions. The removal of tooling from the slides and bolster of an opposed slide double action press, and the replacement of such tooling is both difficult and time consuming and also subjects workmen to hazardous working conditions. In this respect, the position of the bolster between the upper and lower slides confines the available working space to that between the opposite sides of the bolster and the corresponding slide member. Thus, access to fasteners such as bolts which must be removed to achieve release of tooling components is restricted, whereby such removal is both tedious and time consuming.
Even though the tooling components may be mounted on a common support member for removal from one of the slides or bolster as a unit, such removal heretofore has required the use of exterior handling equipment, and the manoeuvring of such handling equipment and a tooling unit during an assembly or disassembly operation. These procedures, in addition to being time consuming and hazardous, require the exercise of care to avoid damage to the tooling components by engagement thereof with other press components. Even if the bolster is mounted on the press frame in a manner which enables removal of the bolster to increase the available work space with respect to tooling on the press slides, such removal of the bolster heretofore has been a time consuming operation and, again, requires the use of special exterior handling equipment for such removal and remplacement and, additionally, the provision of a special bench or support on which the bolster can be placed after removal. Further, the bolster often has tooling on the underside thereof, whereby the special support must enable access to the underside, or the bolster must be further manipulated once removed from the press to gain access to such tooling. Moreover, even though the bolster may be so removed, the tooling on the slides must be released and removed by independent operations.